The cause was a localization problem. For example when you open the gallery viewer (a image) the window is titled 'Gallery Viewer'. The main language for me is german (de-AT,  de-DE) so the window should be titled like 'Galerieanzeige'. I translated all resources for DE but the window titles, the buttons and very rare passages inside the module are static coded (it remain english and can not be translated via the resources). 
I've patched the code and the solution works now for german. Now i've small problem (better nuisance); in the project explorer the files *.ascx.vb, *.aspx.vb and *.resx files which are depended to the *.ascx file aren't show . I must directly open the *.vb file to change the code. It' very annoying when it's not shown what belongs to the project.

maybe you've tip for me how can i change this problem

best wishes
guy